Washington (CNN) – The race to become the Democratic nominee for mayor of Washington, D.C. – a contest that was once defined by a crowded, fractured field – has become a head-to-head competition between incumbent Mayor Vince Gray and Muriel Bowser, a D.C. councilmember.

As voters head to the polls on Tuesday, Bowser has become the most likely challenger to unseat Gray, who a majority of voters believe knew of an illegal shadow campaign that helped him win the mayor's office in 2010.Follow @politicaltickerFollow @danmericacnn

According to a recent Washington Post poll, 30% of likely primary voters support Bowser, a number two times greater than a Post survey in January. Gray has 27% support, a number that has remained steady since the race started. The three percentage point difference between the candidates is within the margin of error, making the race a statistical dead heat.

A NBC4/Marist poll released last week also found Bowser with a slight lead in the race. According to the poll, 28% of likely Democratic voters support Bowser, while 26% back Gray.

Since prosecutors began looking into Gray's first mayoral race, ethics have remained an issue for the longtime D.C. politician. Earlier this month, federal prosecutors sought to link Gray to campaign finance allegations made by Jeffrey Thompson, a Washington businessman who plead guilty to conspiracy for masterminding a nearly $670,000 illegal "shadow campaign" for Gray in 2010.

During the Thompson hearing, prosecutors publicly claimed Gray was aware of the illegal fundraising and had agreed with Thompson to cover it up. Gray has not been charged with any wrongdoing and has vowed that he did not know of the shadow campaign and did nothing wrong.

"I think if you look at my life," Gray told CNN earlier this month, "my life is one that I am very proud of and this situation is one that, at best, I can describe as an anomaly."

Gray said he doesn't feel that he did anything wrong in the 2010 campaign, has operated "openly and honestly," and has no plans to step down.​

Most voters aren't buying it, though.

According to the Post poll, six in 10 likely Democratic primary voters believe Thompson's allegations are true. And 75% of those polled said the investigation into Gray was fair.

Sixty-one percent of Democratic primary voters also said Gray is not "honest and trustworthy," a number that is slightly up from January.

Despite the ethics questions, Gray has led the nation's capital during a time of booming growth and declining crime rates. Washington, D.C. weathered the national economic downturn that crippled other cities and even Gray's mayoral challengers have acknowledged that economic growth in the past four years has boosted the District.

Because of that, among all registered voters, Gray's job approval remains positive. Fifty-three percent of Washingtonians approve of the mayor's job handling, while 39% have a negative view.

A handful of other candidates remain in the race for the Democratic nomination, but none have experienced the jump in support that has propelled Bowser. The Washington Post, for example, endorsed her earlier this month, citing her open mind to new ideas.

Tommy Wells has maintained steady support in the low teens, with 14% of likely primary voters supporting the councilmember. Jack Evans, another member of the D.C. council, was once considered a contender in the race, but the Post's most recent poll found that Evans' support has been cut in half and now only 6% of likely Democratic voters intend to vote for the longtime D.C. politician.

Unlike in years past, where winning the Democratic nomination for mayor meant the winner in November was a foregone conclusion, whoever wins Tuesday's election is likely to face a contentious challenge from independent councilmember David Catania.

Catania launched an independent bid for the office earlier this month, just two days after federal prosecutors said Gray knew about the 2010 shadow campaign. In his announcement, the gay former Republican highlighted "the importance of playing by the rules" and "a strong commitment to fairness."

"We've overcome big obstacles in the past," Catania said in an email to supporters. "And with your support, together, I'm confident that we can meet these challenges."

According to the Post poll, if Gray wins the nomination, his race with Catania will be extremely close. Among all registered voters, both Gray and Catania received 41% support in a hypothetical general election matchup.

If Bowser wins the nomination, however, Catania will have a much more uphill climb to win the mayor's office. According to the poll, Bowser leads Catania by 30 percentage points.

soundoff(13 Responses)

Rudy NYC

It's too bad that the article fails to identify WHEN the Democratic primary is scheduled to take place.

March 31, 2014 12:12 pm at 12:12 pm |

just asking

wow, illegal shadow campaigns and illegal contributions. sure gives us all a glimpse into how the democrats steal elections doesn't it. and they are the ones always claiming others of wrong doing. it is now very clear why they don't want voter id laws. it will stop a good chunk of their other illegal election activity.

March 31, 2014 12:20 pm at 12:20 pm |

Get Real

I do NOT believe there are ANY ETHICAL people in DC.

March 31, 2014 12:20 pm at 12:20 pm |

Dean

Ethics? In a Democrat primary? There's no such thing.

March 31, 2014 12:48 pm at 12:48 pm |

Donna

Why are people voting for a guy that will most likely end up in jail? Oh yeah, this is Washington DC, where even a coke head can get elected. And I guess Democrats are used to voting for criminals anyways. That is what most of their base is made up of.

Just spewing there has only been one stolen election and it was perpetrated by the Bush klan and you know it.

March 31, 2014 01:03 pm at 1:03 pm |

Dominican mama 4 Obama

Rudy NYC
As voters head to the polls on Tuesday, Bowser has become the most likely challenger to unseat Gray

March 31, 2014 01:04 pm at 1:04 pm |

Rudy NYC

"As voters head to the polls on Tuesday, Bowser has become the most likely challenger to unseat Gray, ... ..."

Ah, There it is. Tomorrow.

March 31, 2014 01:11 pm at 1:11 pm |

Silence DoGood

@Rudy NYC
It's too bad that the article fails to identify WHEN the Democratic primary is scheduled to take place.
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Not important: The article is put out there to bait the usual knee-jerk right wingers to start the chorus of "Bad Dems!" to get some cheap and predictable comments.

Of course he knows it, he's looking for someone who's stupid, to join the way he votes, sad huh? The rwnj constantly fish for fools to join the ranks, at the bottom of the uninformed and least intelligent, that's their base,outside of the wealthy who know better, but live SN opulent life because of the people who believe their BS. Every position they take, regardless if issue, is widely contested by experts in that field, here's your sign.

March 31, 2014 01:19 pm at 1:19 pm |

Dominican mama 4 Obama

Oh yeah, this is Washington DC, where even a coke head can get elected.
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Say hello to George W. Bush.

March 31, 2014 01:27 pm at 1:27 pm |

Fair is Fair

This is Washington, D.C. – may the best criminal win.

March 31, 2014 01:29 pm at 1:29 pm |

J Anthony

@Donna: yes only the Democrats do it, sure, get your head out of the sand. If you vote for either wing of the plutocracy, you are voting for things to either stay the same or get worse. Wake up